<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>box-sizing</title>
    <style>
        div {
            width: 250px;
            border: 5px solid red;
            margin: 30px;
        }
    </style>
</head>
<body>
    <div style="box-sizing: content-box">
        1111111111111111111111
    </div>
    <div style="box-sizing: border-box">
        1111111111111111111111
    </div>
</body>
</html>